1) 68 to 70 mph; your tires are speed rated at 65 mph if they are ST's
2) 26 to 36 gallon tank; they kill you on parts; looked at this move on my last F150 and the parts alone were over $1,000. Find a wreck?
3) I'm getting 11.0 to 11.5 pulling a 5,500 lb Survery with my Eco w 3.73s
4) Driving style, speed and conditions will play a far bigger role in gas mileage than gearing. You might get a few tenths with 3.31's or 3.15's but then what can you tow with that?

I will check the tires to see what they are rated at. But the mpg that have gotten has been acceptable to me. I did my best to keep the truck in 6th. That I think is the trick keeping the truck in the highest gear.

I will check the tires to see what they are rated at. But the mpg that have gotten has been acceptable to me. I did my best to keep the truck in 6th. That I think is the trick keeping the truck in the highest gear.

Heck yes! You are getting good mileage when towing! 6th gear gets you the best mileage. That and keeping your speed down. There is a big difference between 65 mph and 60 mph mileage when towing. But it is all a trade-off and what is important to you. Have fun!

I hit 60 and am watching the mirrors for chunks of those crappy Trail Expresses. You guys need to strap a big set of steel balls to the back of your truck! I know mine aren't that tough to push these TT tires that far, lol. Maybe when I get the Kumho's on...

I hit 60 and am watching the mirrors for chunks of those crappy Trail Expresses. You guys need to strap a big set of steel balls to the back of your truck! I know mine aren't that tough to push these TT tires that far, lol. Maybe when I get the Kumho's on...

You will LOVE the Kumho's; they are awesome tires. I mounted some this year and installed a Truck Systems Technologies tire pressure monitoring system. Now I don't worry about missing a tire going low. And the Kumho's are rated for 99 mph (not that you'll use that) and well as D load rating.